Method of manufacturing catheter

ABSTRACT

The invention relates to a method of manufacturing a catheter, wherein the catheter comprises an elongate portion having a proximal end and at least one lumen at said proximal end, at least one extension tube having a passage, and a coupling element, the distal portion of the extension tube being capable of communicating with a lumen of the elongate portion via a passage in the coupling element wherein the method comprises a step wherein a removable insert element locates and holds the extension tube in contact with the elongate portion during the manufacture of a coupling element. The invention also relates to a removable insert for use in the manufacturing of catheters.

The present invention relates to catheters which can be inserted intothe human or animal body for various medical purposes. More particularlythe present invention relates to catheters formed by moulding.

BACKGROUND OF THE INVENTION

A catheter includes an elongate slender flexible portion for insertioninto a body cavity such as a vein or artery. The elongate portion has atleast one lumen, but typically has a plurality of lumens, and extendsfrom a proximal end at a coupling element to a distal end, which in useis inside the human or animal body. The lumens within the elongateportion can be used to introduce or remove fluid from the human oranimal body or alternatively carry means allowing measurement of bloodpressure, blood flow or such like. As each lumen typically containsdifferent means performing different functions, the means within eachlumen may be attached to particular components or equipment. The meanswithin each lumen within the elongate portion are connected toparticular components or equipment via extension tubes, which attach tothe proximal end of the lumens of the elongate portion via the couplingelement.

The extension tubes are commonly attached to the proximal end of thelumens of the elongate portion via plastic adapters. These plasticadapters may be glued in position using adhesive such that the adhesivebonds the extension tube to the elongate portion. However this method ofgluing adapters to the extension tube is very labour intensive andrequires long drying times for the adhesive to set and harden. Further,the adhesive may flow into one or more of the lumens of the elongateportion and completely or partially block the lumens.

An alternative method used, that eliminates the need for gluing, is theinsertion of wire mandrels through an extension tube and into a lumen ofthe elongate portion. A mould tool is then placed around the elongateportion and extension tube and a coupling element formed by mouldingplastic into the mould tool. The coupling element formed around theextension tube and the proximal end of the elongate portion, secures theextension tube to the elongate portion. Removal of the wire mandrelsfrom the lumens of the elongate portion and from the extension tubecreates passages in the coupling element allowing passage of fluid orother means from the extension tube into the lumens of the elongateportion.

This alternative method of attaching the extension tubes to the elongatemember also has a number of disadvantages in that large diameterextension tubes or elongate portions tend to melt in the mould, whilesmall diameter extension tubes or elongate portions allow the plasticbeing moulded to “flash” out of the mould alongside the extension tubesor elongate portions. In addition the hot plastic used for moulding cancause kinking or collapse of the lumens within the elongate portion.

The moulding method described above to attach the extension tubes to theelongate portion has been improved by including an insert element in thecatheter as described in U.S. Pat. No. 4,670,009. The insert element ofthe catheter surrounds the extension tubes, holding the extension tubesin place in the finished catheter and preventing the injected plasticfrom “flashing” out around the extension tubes during the mouldingprocess. During manufacture the use of an integral insert element in thecatheter means the mould need not be sized to accommodate any particularnumber or diameter of extension tubes, provided the mould can close offaround the insert element such that no plastic flashes through themoulding insert interface.

The use of an insert element which is incorporated into the finalcatheter product to secure the extension tubes to the elongate elementrequires that the integral insert element is pre-fabricated for eachcatheter being produced. The fabrication of an integral insert elementadds to the cost of the production of the catheter. Further the use ofan integral insert element in the catheter adds to the number ofcomponents and material within the catheter and this again contributesto the production cost of the catheter.

It would be advantageous if a catheter could be produced which did notrequire an integral insert element to be fabricated for and included ineach catheter produced. The use of a releasable insert element(s) or aninsert element integral to the mould tool would be advantageous as theuse of such an insert would reduce the expense of fabrication of thecatheter and further reduce the cost of the material required to makethe catheter.

SUMMARY OF THE INVENTION

According to the present invention there is provided a method ofmanufacturing a catheter wherein the catheter comprises an elongateportion having a proximal end and at least one lumen at said proximalend, at least one extension tube having a passage, and a couplingelement, the distal portion of the extension tube being capable ofcommunicating with a lumen of the elongate portion via a passage in thecoupling element wherein the method comprises the use of a removableinsert element to locate and hold the extension tube during themanufacture of coupling element.

The invention further provides a catheter made according to this method.

Accordingly the invention provides a removable insert to locate and holdat least one extension tube during the manufacture of a catheter.

Preferably the removable insert element is comprised of metal,composite, or high melting temperature plastic.

Preferably the removable insert element is capable of being positionedin the mould tool to locate the extension tubes within the couplingelement.

Preferably the removable insert element is formed of a single section.

Alternatively the removable insert element is formed by a plurality ofsections.

Preferably the coupling element includes plastic material which ismoulded over the elongate element.

Preferably the catheter comprises a plurality of extension tubes and theelongate portion comprises a plurality of lumens, the passages ofextension tubes corresponding with the respective lumens of the elongateportion.

Alternatively the catheter comprises a plurality of extension tubes andthe elongate portion comprises a plurality of lumens, wherein a passageof an extension tube corresponds with at least two lumens of theelongate portion.

Preferably the passages in the coupling element are formed using wiremandrels extending from the extension tubes into the lumen of theelongate portion.

Preferably the elongate portion is flexible and sized to be receivedwithin the vein or artery.

Prefereably the removable insert element provides a recess volume in thecoupling element to accept an extension tube.

Alternatively the removable insert element may create a feature toconnect at least one extension tube to at least one lumen of theelongate portion.

Preferably a mandrel guide is used to position the wire mandrelsextending from an extension tube into a lumen of the elongate portion.

Preferably a mandrel guide is used to position the wire mandrels incombination with a releasable insert element.

Preferably the mandrel guide has locating features on a first endwherein the locating features are capable of locating the mandrel guidein a particular orientation relative to the removable insert element.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way ofexample only with reference to the accompanying drawings in which

FIG. 1 is an isometric view of the catheter,

FIG. 2 is a sectional view of the catheter along line 2-2,

FIG. 3 is an enlarged sectional view along line 3-3,

FIGS. 4 a and b are isometric drawings depicting the main steps involvedin forming the catheter,

FIG. 5 shows a removable insert able to create a recess volume in theconnecting element to accept an extension tube,

FIG. 6 shows a removable insert able to connect an extension tube tomore that one lumen of the catheter body,

FIG. 7 shows a mandrel guide, and

FIG. 8 shows an alternative mandrel guide.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a catheter 10 which comprises an elongate portion 12,extension tubes 14, and a connecting element 16. The connecting element16 receiving at least part of the extension tube 14 and the elongateportion 12 such that it is capable of retaining these within theconnecting element 16.

In the embodiment shown in FIG. 1 the elongate portion 12 comprises fourlumens 18 although different elongate portions could contain greater orfewer numbers of lumens. In the embodiment shown in FIG. 1 each of thelumens 18 of the elongate portion 12 correspond to a distinct passage 20of an extension tube 14. Each particular extension tube 14 may beconnected to different pieces of equipment (not shown) to allow each ofthe lumens 18 to contain different elements such as conductive wires,thermistors, pressure sensing apparatus, means for infusing solutions orthe like.

The elongate portion 12 may be constructed of a biocompatible plasticmaterial such as PVC, the proximal end 22 of the elongate portion 12being received by the coupling means 16. The extension tubes 14 may beof equal or different diameter to each other and may be constructed of asuitable plastics material such as PVC.

The coupling element 16 is also constructed of a suitable plasticsmaterial such as polyester or low melting temperature plastic, metal orcomposite, which allows it to be bonded to the plastic of the elongateportion 12 and the extension tubes 14 during the moulding process. Asshown in FIG. 2 wire mandrels 24 are passed through the passages 20 ofthe extension tubes 14 into the lumens 18 of the elongate portion 12such that during the moulding process they are able to form passages 42in the coupling element linking the elongate portion 12 to the extensiontubes 14.

Moulding of the coupling element may be performed by any means known inthe art including introducing powdered plastic into the mould tool andheating the mould or injecting plastic into the mould tool. In theembodiment described injection moulding is the preferred method offorming the coupling element.

During the moulding process a removable insert 28 is used to hold theextension tubes 14 in place within the coupling means 16 and prevent theplastic from flashing out of the mould at the position at which theextension tubes exit the mould tool 32.

The removable insert element 28 may be constructed of metal, compositeor a suitable high melt plastic. The removable insert element comprisesat least one passage 34. In the embodiment shown four passages arepresent that extend through the removable insert element 28 from a firstface of the removable insert element 28, which faces the elongateelement to a second opposite face. The passage 34 through the removableinsert element 28 is sized such that it grips extension tube 14 pushedthrough the passage 34 of the removable insert element 28. Further theremovable insert element 28 may comprise a flange portion 29 to aidlocation of the removable insert element 28 in the mould tool 32.

As shown in FIGS. 4 and 5 the preferred method of manufacturing thecatheter is a predetermined portion 15 of at least one extension tube 14is passed through the passage 34 of the removable insert element 28 suchthat the portion 15 of the extension tube 14 extends beyond the secondface of the removable insert element 28 such that when the removableinsert element 28 is located within the mould tool 32, the portion 15 ofthe extension tube 14 which extends beyond the removable insert element28 enters into the space 30 within the mould tool 32 into which theplastic is to be injected or entered into the mould.

As the extension tubes 14 are frictionally held within the passages 34of the removable insert element 28 when the removable insert element islocated within the mould tool 32, the extension tubes 14 are suitablylocated in the coupling element 16 when it is formed by the mouldingprocess.

The elongate portion 12 is located and held by the coupling element 16using a sleeve 36. The sleeve 36 is a thin walled flexible tube, capable(using its inner face 38) of tightly gripping the outer face of theproximal end of the elongate portion 12.

The sleeve 36 being attached to the connecting element 16 via its outerface 40 during the moulding process.

During the manufacture of the catheter the sleeve 36 containing theelongate portion is suitably positioned in the mould tool 32 such thatthe coupling element can be around it.

The sleeve 36 is pliable such that it is able to take up variances inthe diameter of the elongate portion 12 created during the production ofthe elongate portion 12.

Wire mandrels 24 are inserted through the extension tubes 14 and intothe respective lumens 18 of the elongate portion where they are held inplace by friction. Removal of the wire mandrels 24, following mouldingenables passages through the coupling element 16 to be created.

As shown in FIG. 4 b the mould tool 32 comprises sections 50 and 52which can be moved relative to each other away from each other to anopen position or toward each other to a closed position. In the openposition the removable insert element 28 can be located within the mouldtool 32. The sleeve 36 can also be positioned in the mould tool 32, thesleeve 36 gripping the proximal end of the elongate tube 12 such that itwill be suitably located within the coupling element 16 when thecoupling element is formed by the moulding process.

Once the removable insert element 28 and sleeve 36 have been located inthe mould tool, mould tool sections 50 and 52 can be moved to a closedposition such that the mould tool 32 forms a tight fit around theremovable insert element 28. Further the closed mould tool has a tightfit around the sleeve 36.

When the mould tool sections 50 and 52 are in the closed position, hotplastic may be injected or entered into the space 30 via inlet 54 toform the connecting element 16. The tight fit of the removable insertelement 28 ensures that no plastic flashes out around the removableinsert element 28, while the tight fit of the mould tool 32 around thesleeve 36 ensures that plastic cannot flash out between the mould tool32 and the sleeve 36.

The grip of the sleeve 36 on the elongate portion 12 further ensuresthat plastic cannot flash out between the sleeve 36 and the elongateportion 12.

The plastic of the coupling element 16 forms around the portion 15 ofthe extension tubes 14, which extends beyond the removable insert means28 into the cavity 30, and the sleeve 36, which grips the elongateportion 12. Once cured the plastic which forms the coupling elementtherefore holds the extension tubes 14 and the sleeve 36 in the couplingelement 16, but does not grip or attach the removable insert element 28.

The injected plastic and plastic entered into the mould tool flowsaround the wire mandrels 24 causing the mandrels when removed to leavepassages 42 through the coupling element. After the plastic of thecoupling element cures the mould sections 50 52 can be relatively movedaway from each other to an open position. The extension tubes 14 arepulled through the passages of the removable insert element 28 and thecatheter including extension tubes 14, wire mandrels 24, connectingelement 16, sleeve 36 and elongate member 12 can be removed from themould. The removable insert means may then be reused to hold extensiontubes to form a second or subsequent catheter, saving on material andproduction costs of insert elements.

The wire mandrels 24 can then be removed from the extension tubes 14 andlumens 18 of the elongate portion 12 to form passages 42 in the couplingelement 16.

In an alternative embodiment of the present invention the wire mandrels24 may be held in position within the mould tool 32 by a mandrel guidemember 60. This mandrel guide member 60 can be of any suitable shapesuch that it can be positioned between the wire mandrels 24. The mandrelguide member 60 having a series of grooves 62 around its perimeter inwhich the wire mandrels 24 can be located to suitably position them inthe coupling element 16.

The mandrel guide member 60 prevents the wire mandrels 24 touching eachother and thereby prevents interpassage leaks in the coupling element16.

As shown in FIGS. 7 and 8 the mandrel guide may be cylinder shaped orcone shaped depending on how the mandrels are to be arranged.

Various embodiments of the present invention can be envisaged withoutdeparting from the scope of the present invention. For example theremovable insert element 28 may be shaped as shown in FIG. 5 with aprotrusion 70 extending from the surface of the removable insert element28 which contacts the coupling element during moulding. This protrusion70 may be used to create a recess volume 74 in the coupling element 16,this recess volume 74 providing a feature which allows the attachment ofan extension tube 12 at a period after formation of the coupling element16.

Alternatively the removable insert element 28 may be shaped such that itis able to connect one extension tube to more than one lumen in theelongate member. As shown in FIG. 5, a larger passage 72 may be createdin the removable insert element 28 able to accommodate an extension tubeinto which a plurality of mandrels linking to a plurality of lumens 18in the elongate portion 12 can be placed.

1. A method of manufacturing a catheter wherein the catheter comprisesan elongate portion having a proximal end and at least one lumen at saidproximal end, at least one extension tube having a passage, and acoupling element, the distal portion of the extension tube being capableof communicating with a lumen of the elongate portion via a passage inthe coupling element wherein the method comprises: providing a removableinsert element wherein said removable insert element locates and holdsthe extension tube during the manufacture of the coupling element;inserting a wire mandrel through an extension tube and into a lumen ofthe elongate portion; positioning the removable insert in a mold tool tolocate the extension tube within the coupling element such that plasticis prevented from flashing out of the mold at the portion at which theextension tube exits the mold; forming the coupling element in the moldtool wherein the removable insert is positioned in the mold tool tolocate the extension tube within the coupling element; and removing: (i)the wire mandrel from the lumen of the elongate portion and from theextension tube to create a passage in the coupling element from theextension tube into the lumen of the elongate portion; and (ii) theremovable insert element from the coupling element.
 2. The method asclaimed in claim 1, further comprising fabricating the removable insertfrom one of a metal, composite, and high melting temperature plasticmaterial.
 3. The method as claimed in claim 1, further comprisinglocating the removable insert to provide at least one recess volume inthe coupling element to accept an extension tube.
 4. The method asclaimed in claim 1, further comprising providing the removable insertelement with means to connect at least one extension tube to at leastone lumen of the elongate portion of a catheter.
 5. The method asclaimed in claim 1, wherein a mandrel guide is used to position the wiremandrel extending from an extension tube into a lumen of the elongateportion.
 6. The method as claimed in claim 1, wherein a mandrel guide isused to position the wire mandrel in combination with the removableinsert element.
 7. The method as claimed in claim 6, further comprisingproviding the mandrel guide with locating features on a first end, thelocating features being capable of locating the mandrel guide in aparticular orientation relative to the removable insert element.